Alzheimer's disease (AD) is a chronic progressive neurodegenerative disease. Clinically, it is characterized by progressive deficits in memory and other cognitive functions that occur in the face of an otherwise normal neurological examination. Postmortem examination reveals a variety of typical AD brain lesions, including deposition of amyloid plaques, formation of neurofibrillary tangles, and neuronal degeneration. The etiology and pathophysiology of neuronal death are unknown.
Despite the fact that Alzheimer's disease is the most common neurological disease in the United States, there are no reliable antemortem biological tests for its diagnosis. Currently diagnosis rests on clinical grounds, and thus accuracy depends on the degree of physician expertise. An objective method for antemortem diagnosis of AD would be extremely useful: it would distinguish AD from other forms of dementia which may be curable; it would enable the patient to enter a treatment program early in the development of the disease, thus enhancing the opportunity for beneficial therapy; and it would allow patients in the early stages of the disease to plan for future nursing care, as well as to address other issues concerning the future needs of the patient's family.